I'd just like to point out, that I run a side business selling vinyls/cassettes in a very niche genre. I looked into advertising on reddit, as there were two or three communities that I was already active in with collectors of this type of music.
I thought it'd be better to advertise than self promote. However, Reddit's ad management is a complete cluster. It is confusing, frustrating to set up, and difficult to analyze.
The reason I really wanted to advertise on Reddit rather than Facebook/Instagram is that Facebook's "profiles" of people aren't specific enough for what I am selling. But with Reddit, I literally just want to target anyone who is a member of or visits these specific subreddits.
For me, it is perfect targeted advertising without any invasive tracking of users!
But Reddit wouldn't let me. Those subreddits aren't on their very limited list of approved subreddits. Instead my only choice was to be able to target a really, really big subreddit (/r/Music) which 99.99% of the people there would have no interest in my product, or to use their profiles, which are not nearly as complete as Facebook's.
So, I gave up, and decided I wasn't getting my return on advertising on Reddit.